Test adding strings at end of TextBuffer

core/src/text_buffer/mod.rs

@@ -45,6 +45,16 @@ impl TextBuffer {
         }
     }
 
+    pub fn insert_text(&mut self, text: impl Into<String>, point: Point) {
+        match point {
+            Point::End => {
+                self.contents = self
+                    .contents
+                    .insert_at_char_index(self.contents.total_chars(), text);
+            }
+        }
+    }
+
     pub fn insert_char(&mut self, c: char, point: Point) {
         match point {
             Point::End => {
@@ -154,4 +164,29 @@ mod tests {
         assert_eq!(16, target.num_chars());
         assert_eq!(5, target.num_lines());
     }
+
+    #[test]
+    fn insert_text_at_end_increases_counts_as_expected() {
+        let mut target = TextBuffer::new();
+        target.insert_text("The", Point::End);
+        assert_eq!(3, target.num_bytes());
+        assert_eq!(3, target.num_chars());
+        assert_eq!(1, target.num_lines());
+        target.insert_text(" ", Point::End);
+        assert_eq!(4, target.num_bytes());
+        assert_eq!(4, target.num_chars());
+        assert_eq!(1, target.num_lines());
+        target.insert_text("quick brown", Point::End);
+        assert_eq!(15, target.num_bytes());
+        assert_eq!(15, target.num_chars());
+        assert_eq!(1, target.num_lines());
+        target.insert_text(" fox\n", Point::End);
+        assert_eq!(20, target.num_bytes());
+        assert_eq!(20, target.num_chars());
+        assert_eq!(1, target.num_lines());
+        target.insert_text("jumps over the lazy 猫.", Point::End);
+        assert_eq!(44, target.num_bytes());
+        assert_eq!(42, target.num_chars());
+        assert_eq!(2, target.num_lines());
+    }
 }